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Physiology > The Nervous System (Topic 8) > Flashcards

The Nervous System (Topic 8) Flashcards

1
Q

What are the two major divisions of the nervous system? (1)

A

central and peripheral

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2
Q

Are neurons mitotic or amitotic? (2)

A

amitotic

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3
Q

Characteristics of neurons (2)

A
  • Have a very high metabolic rate.
  • Make up only 10% of cells in nervous system.
  • The rest are glial cells. (Provide physical and metabolic support)
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4
Q

What is the structure of a neuron? (3)

A

dendrites branch from the cell body, and axon branches down from the cell body into the axon terminals

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5
Q

Do dendrites send or receive signals? (3)

A

receive

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6
Q

What are the different types of neurons? (3)

A
  • bipolar (interneuron)
  • unipolar (sensory neuron)
  • multipolar (motoneuron)
  • pyrimidal cell
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7
Q

What is a nucleus? (4)

A

cluster of cell bodies in the central nervous system (in medulla region)

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8
Q

What is ganglion? (4)

A

cluster of cell bodies in the peripheral nervous system

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9
Q

What is a nerve? (4)

A

bundle of axons that send signals to/from the CNS

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10
Q

What does a synapse do? (5)

A

releases neurotransmitters to stimulate the next cell

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11
Q

Cells referred to by position in relation to synapse are called what? (5)

A

presynaptic or postsynaptic

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12
Q

What are four types of glial (support) cells? (6)

A
  • astrocytes: from tight junctions
  • microglia: macrophage-like cells
  • ependymal cells: ciliated (produce and circulate cerebrospinal fluid)
  • oligodendrocyte: myelin
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13
Q

What do astrocytes do? (7)

A

support cells
- control extracellular environment of neurons
- Form tight junctions of the blood-brain barrier

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14
Q

What do microglia do? (7)

A

macrophage-like cells that conduct phagocytosis to remove debris

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15
Q

What do ependymal cells do (7)

A

produce and circulate CSF

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16
Q

What do oligodendrocytes do? (7)

A

they’re sheaths on multiple axons

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17
Q

What two types of glial cells are in the PNS? (7)

A

staelitle cells and shwann cells

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18
Q

What are satellite cells? (7)

A

nourish neurons

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19
Q

What do shwann cells do? (7)

A
  • form myelin sheaths
  • guide growth during development and regeneration
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20
Q

What is myelin? (8)

A

20-200 layers of modified plasma membrane wrapped around the axon of a neuron

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21
Q

What does myelin do? (8)

A

-insulates axon
- speeds up signals

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22
Q

How is myelin formed? (8)

A
  • PNS: schwann cells
  • CNS: oligodendrocytes
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23
Q

What is the resting membrane potential range? (10)

A

-40 to -90 mV

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24
Q

What causes change in membrane potential? (10)

A

ions moving in or out of the cell??

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25
Q

Cells, under resting conditions, are ____charged inside with respect to the extracellular fluid (10)

A

negatively

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26
Q

How is membrane potential maintained? (11)

A

constant breakdown of ATP

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27
Q

How is the concentration gradient maintained? (11)

A
  1. Na+/K+ pumps
  2. open ion channels “leak”
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28
Q

What do Na+/K+ pumps do? (11)

A

moves 3+ out for every 2+ that comes in, decreasing membrane potential

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29
Q

What do open ion channels “leak” do? (11)

A
  • move Na+ into the cell
  • move K+ out of the cell
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30
Q

What are two types of changes in membrane potential? (12)

A

graded and action potentials

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31
Q

What is depolarization? (12)

A

moving from resting membrane potential to less negative values

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32
Q

What is repolarization? (12)

A

polarization moving back to the resting membrane potential.

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33
Q

What is hyperpolarization? (12)

A

moving more negative than resting membrane potential

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34
Q

What are characteristics of graded potentials? (13)

A
  • Confined to small region of the plasma membrane, so can only signal over short distances.
  • Magnitude of the potential can vary.
  • May be depolarizing or hyperpolarizing.
  • Current is decremental:
    Examples: receptor potential, synaptic potential, and pacemaker potential potential
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35
Q

Characteristics of action potentials (14)

A
  • not graded, all-or-nothing
  • Large change in membrane potential
  • Very rapid (as brief as 1–4 ms) and may repeat at >100 Hz
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36
Q

What is excitability? (14)

A

the ability to generate action potentials

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37
Q

What type of cells does excitability happen in? (14)

A

neurons and muscle cells

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38
Q

Graded potential may be due to ___? (14)

A

Ligand-gated, mechanically-gated, and voltage-gated channels may offer the initial stimulus

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39
Q

What are graded potentials required for? (14)

A

required to trigger action potentials.

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40
Q

What is an action potential? (14)

A

Rapid depolarization and repolarization performed by voltage-gated channels

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41
Q

What do Na+ and K_ channels open and close in response to? (15)

A
  • Open in response to depolarization
  • Close with repolarization
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42
Q

Study slide 16 on action potentials!!!!

A

DO IT! DONT BE DUMB!

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43
Q

What is a threshold stimulus? (19)

A

a stimulus that is just strong enough to trigger an action potential

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44
Q

What is a subthreshold stimulus? (19)

A

a stimulus not strong enough to trigger an action potential

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45
Q

What is a subthreshold potential? (19)

A

a depolarization that does not reach threshold

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46
Q

If ‘all-or-nothing’, how do we distinguish a light touch from a pinch? (19)

A

the amount of action potentials (the frequency of action potentials increases)

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47
Q

What prevents action potentials? (20)

A

local anesthetics block voltage-gated sodium channels

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48
Q

How does blocked voltage-gated sodium channels stop pain? (20)

A

preventing sodium flowing, prevents depolarization, which prevents the action potential
- without the action potential, nothing is felt

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49
Q

How can voltage-gated sodium channel blockers lead to death? (20)

A
  • causes no signals to be sent
  • leads to cellular and respiratory failure and paralysis
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50
Q

What is the absolute refractory period? (21)

A
  • a second stimulus, no matter how strong, will not produce a second action potential.
  • voltage-gated Na+ channels are either open or inactivated
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51
Q

What is the relative refractory period? (21)

A

second action potential can be produced, but only if the stimulus strength is considerably greater than usual.

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52
Q

What does the relative refractory period correspond to? (21)

A

closed sodium ion channels and hyperpolarization of the membrane

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53
Q

What is needed to get from hyperpolarized state to threshold? (21)

A

bigger change in membrane potential to get from hyperpolarized state to threshold

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54
Q

Why does it take a smaller stimulus to reach threshold over time after hyperpolarization? (21)

A

over time, the membrane potential gets closer and closer to resting so it doesn’t take as much to reach threshold
(- the membrane potential is back to resting
- hyperpolarization is over
- the refractory period is over)

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55
Q

What does the refractory period do to the action potential? (22)

A

makes it unidirectional (one way)
- from the cell body to the axon terminal

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56
Q

Where does the first action potential take place? (22)

A

axon hillock/ initial segment

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57
Q

What has a bidirectional action potential?

A

muscles

58
Q

What is myelin? (23)

A

Myelin is an insulator that makes it more difficult for charge to flow between intracellular and extracellular fluid compartments

59
Q

Where do saltatory (jumps) action potentials occur? (23)

A

occur only at the nodes of Ranvier
- Faster than in unmyelinated neurons (100 m/s vs. 0.5 m/s).
- Membrane pumps need to restore fewer ions (metabolically cheaper).

60
Q

Go through slide 24: Graded vs. Action potentials (24)

A

Whoop Whooop

61
Q

What is a synapse? (25)

A
  • connections between neurons/ neurons and effectors
  • sites for chemical exchange
62
Q

Convergence vs divergence (25)

A

convergence: multiple pre-synapses to single post-synapses
divergence: single pre-synapse to multiple post-synapses

63
Q

How do you know you’re falling? (25)

A

single pre-synapse diverge to multiple post-synapses

64
Q

What are two types of synapses? (26)

A

electrical and chemical

65
Q

What are electrical synapses? (26)

A

electrical activity of the presynaptic neuron affects the electrical activity of the postsynaptic neuron.
- Rare, connected by gap junctions
- very fast, but no control in the second neuron

66
Q

What are chemical synapses? (26)

A

utilize neurotransmitters.
- Pre-synaptic neurons release neurotransmitter from their axon terminals
- Neurotransmitter binds to receptors on post-synaptic neurons
- has control in the second neuron, but is slower compared to electrical

67
Q

Where are neurotransmitters produced and stored? (27)

A

in the vesicles at the axon terminal

68
Q

What is the active zone? (27)

A

area where vesicles are docked

69
Q

How do Intracellular Ca2+ levels increase and stimulate the vesicles to bind to the plasma membrane? (27)

A

Via SNARE proteins

70
Q

how are neurotransmitters released? (27)

A

exocytosis

71
Q

PRACTICE SLIDE 28

A

YAY will be on exam

72
Q

Explain slide 28

A
  • ap reaches axon terminal
  • opens calcium channels
  • calcium moves in
  • neurotransmitter is released
  • neurotransmitter binds to ligand-gated ion channel receptor
  • sodium moves in and depolarizes
  • depolarization hits threshold and causes an action potential
73
Q

What happens to vesicles in synaptic clefts? (29)

A
  • Completely fuse with membrane and eventually recycled by endocytosis.
  • ‘kiss-and-run fusion’
74
Q

Explain the removal of a neurotransmitter (29)

A
  1. Diffusion of the transmitter from the cleft
  2. Degradation of the transmitter by enzymes
  3. Reuptake into the pre-synaptic cells for reuse
75
Q

Why are neurotransmitters removed? (29)

A

to stop the signaling

76
Q

synapses may be what? (30)

A
  • excitatory (depolarization)
  • inhibitory (hyperpolarization)
77
Q

What do excitatory postsynaptic potentials (EPSP) do? (30)

A

bring the membrane potential closer to threshold for generating an action potential.

78
Q

What do inhibitory postsynaptic potentials (EPSP) do? (30)

A

Make membrane potential more negative, making it harder to generate an action potential.

79
Q

What are some characteristics of synaptic integration? (31)

A
  • One EPSP is not enough to reach threshold.
  • EPSPs and IPSPs may occur in the same neuron.
  • Temporal summation -> from same presynaptic cell at different times.
  • Spatial summation -> inputs from different locations
80
Q

Can you have a graded potential that doesn’t reach threshold? (31)

A

yes

81
Q

What does an axo-axonic synapse do? How does it regulate in the membrane? (32)

A

Can influence one neurons effect on another.
- Presynaptic inhibition
- Presynaptic facilitation

82
Q

What do autoreceptors do? (32)

A

provide negative feedback on secretion of neurotransmitters

83
Q

Explain what Presynaptic inhibition and facilitation is based on slide 32

A

A influences how much neurotransmitter comes from B
- if its more, its called facilitation
- if its less, its called inhibition

84
Q

Characteristics of postsynaptic receptor regulation (32)

A
  • can be up or down-regulated
  • receptors can become desensitized (when there’s a lot of neurotransmitter, receptors desensitize)
85
Q

What do many nervous system drugs act on? (33)

A

synaptic mechanisms

86
Q

What is an agonist? (33)

A

increased response

87
Q

What is an antagonist? (33)

A

inhibits response

88
Q

What is botulism? What does it come from? How does it happen? (33)

A
  • muscle paralysis
  • clostridium botulinum (botulinum toxin)
  • messed up canned food
89
Q

What is the common name of botulinum toxin? What are its uses? (33)

A
  • botox
  • prevents wrinkles
  • excessive sweating
  • spasms
90
Q

What does clostridium tetani (tetanus toxin) do? (33)

A
  • Destroys SNARE proteins
  • Inhibits neurotransmitter release
  • Causes increased muscle contraction
91
Q

What neuron does tetanus toxin target? (33)

A

axo-axonic inhibitor synapses

92
Q

What does botulinum toxin do? (33)

A

interferes with SNARE proteins at excitatory synapses that activate muscles

93
Q

Look through slide 34!

A

woo

94
Q

What two classes of chemicals are presumed to be neurotransmitters? (35)

A
  • Acetylcholine (ACh)
  • Biogenic amines
95
Q

What are biogenic amines? (36)

A

Small, charged molecules that are synthesized from amino acids.

96
Q

What are catecholamines made from? (36)

A

tyrosine

97
Q

What is acetylcholine used in? (37)

A

both the PNS and CNS

98
Q

What are cholinergic neurons? (37)

A

Neurons that use ACh as the primary neurotransmitter

99
Q

What are the two types of ACh receptors? (37)

A
  • Nicotinic (Na+ ion channels)
  • Muscarinic (G protein coupled) (Alter activity of a number of different enzymes and ion channels)
100
Q

Where are nicotinic receptors found? (37)

A

at the neuromuscular junctions of skeletal muscles.
- Also found in reward pathways in the brain and autonomic ganglia

101
Q

Where are muscarinic receptors found? (37)

A

found in brain and where PNS innervates organs & glands.

102
Q

Where is ACh produced? (37)

A

produced in the presynaptic axon by the enzyme choline acetyl transferase (CAT)
- Acetyl CoA + choline -> acetylcholine + CoA

103
Q

How is ACh degraded? (37)

A

acetylcholinesterase (AChE or ACE)

104
Q

What do organophosphates do? (37)

A

inhibit ACE

105
Q

How might an organophosphate kill an insect? (37)

A
  • ACE is inhibited
  • ACh increases
  • too much nerve signaling and muscle contraction (overstimulated nervous system that leads to overstimulated muscle contraction)
  • they will twitch till all energy is used up
106
Q

Would organophosphates be hurtful to people? (37)

A

Yes, in large doses

107
Q

What are the divisions of the PNS? (38)

A
  • afferent (toward CNS)
  • efferent (away from CNS)
108
Q

Characteristics of the brain (39)

A
  • (2% of mass, 15% of blood supply)
  • Can only utilize glucose, and has virtually no reserve.
  • Brain cells die in 5-10 min without blood.
109
Q

What are the parts of the cerebrum? (40)

A
  • cortex (gray matter)
  • medulla (white matter)
  • nuclei
110
Q

What is the cortex composed of? What does it do? (40)

A

composed of cell bodies
- processing/ integration of signal

111
Q

What is the medulla composed of? What does it do? (40)

A

composed of axons
- sends signals

112
Q

What is the nuclei composed of? What does it do? (40)

A

clusters of cell bodies
- processing/integration of signals

113
Q

What is the nuclei composed of? What does it do? (40)

A

clusters of cell bodies
- processing/integration of signals

114
Q

Characteristics of the hypothalamus (41)

A
  • Single most important controlarea for homeostasis
  • Centers for processing thirst, hunger, reproduction, etc.
  • Connected to the pituitary gland.
115
Q

What systems does the hypothalamus bridge? (41)

A

endocrine and nervous systems

116
Q

Characteristics of the limbic system (41)

A
  • Spans several regions of the brain.
  • Contain many nuclei.
117
Q

What are the processes of the limbic system? (41)

A
  • emotions
  • motivations
  • moods
  • motor learning
118
Q

How many pairs of cranial nerves are there? (42)

A

12
- motor
- sensory
- mixed

119
Q

How many pairs of cranial nerves are there? (42)

A

12
- motor
- sensory
- mixed

120
Q

What do most cranial nerves do? (42)

A

most innervate with the head and neck

121
Q

What does the vagus nerve innervate? (42)

A

organs in the thorax and abdomen

121
Q

What does the vagus nerve innervate? (42)

A

organs in the thorax and abdomen

122
Q

What is the spinal cord protected by? (43)

A

cord protected by bone (vertebral arch)

123
Q

WHat are the parts of the spinal cord? (43)

A
  • central gray matter
  • white matter
  • 31 pairs of nerves (mixed)
124
Q

What is the gray matter in the spinal cord made of? (43)

A
  • Butterfly-shaped
    Composed of:
  • Interneurons
  • cell bodies
  • dendrites of efferent neurons
  • axons of afferent neurons
  • glial cells
125
Q

What is white matter in the spinal cord made of? (43)

A

myelinated axons

126
Q

What does the somatic nervous system consist of? (44)

A

a single neuron between CNS and skeletal muscle cells

127
Q

What does the somatic nervous system do? (44)

A
  • innervates skeletal muscle
  • can lead only to muscle excitation
128
Q

is the somatic nervous system voluntary or involuntary? (44)

A

voluntary

129
Q

What does the autonomic nervous system consist of? (44)

A

two-neuron chain between CNS and effector organ

130
Q

What does the autonomic nervous system do? (44)

A
  • innervates smooth and cardiac muscle, glands, and GI neurons
  • can be either excitatory or inhibitory
131
Q

Is the autonomic nervous system voluntary or involuntary? (44)

A

involuntary

132
Q

What does the sympathetic nervous system do? (45)

A

gets you ready for stress
- “fight or flight”

133
Q

What does the parasympathetic nervous system do? (45)

A

targets the heart (decreases heart rate)
- “rest and digest”

134
Q

Make sure slide 46 makes sense to you

A

Yeah it makes sense

135
Q

Make sure slide 47 makes sense to you

A

Yeahhhh it makes sense

136
Q

What is an autonomic ganglion? (47)

A

sites at which information (action potentials) arising from the central nervous system (CNS) is transmitted to the periphery via synaptic neurotransmission

137
Q

steps of parasympathetic division (47)

A
  • action potential reaches ganglion
  • ACh binds to a nicotinic receptor
  • sodium channels open and lets sodium into the postsynaptic cell
  • membrane potential depolarizes to threshold
  • action potential is made
  • calcium channels open
  • SNAREs are activated?
  • exocytosis occurs?
  • binds to muscarinic receptors? (form G-protein)?
138
Q

steps of sympathetic division (47)

A

go over graph on slide 47

139
Q

What does the enteric nervous system do? (47)

A

Controls peristaltic contraction in digestive system

Physiology (15 decks)

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